1. Technical Field
The present invention relates to a shape sensor to detect a shape of a measurement target object, and a tubular insertion system having the shape sensor mounted therein.
2. Description of Related Art
An endoscope inserting section that has a curving section and is inserted into a body cavity bends along curves in the body cavity. For example, Japanese Patent No. 4714570 describes a shape detection probe (which will hereinafter be referred to as the shape sensor) that is assembled to the inserting section of the endoscope, bends integrally with the inserting section, and detects a bent shape. Herein, detection light emitted from a light source to detect a curvature is transmitted to a distal end side through a light supply fiber.
At an exit end of the light supply fiber, a mirror is provided, and reflected light of the detection light reflected by the mirror enters a curvature detection fiber, and this reflected light is received by a light receiving element. Further, in the vicinity of a surface of the curvature detection fiber, optical loss sections that absorb a part of the reflected light are provided. Amounts of the reflected light absorbed by the optical loss sections differ depending on curvatures of fiber bundles at positions where the optical loss sections are provided. Thus, in the patent literature, there is described a configuration to calculate the curvatures of the fiber bundles based on intensities of the reflected lights before and after passing through the optical loss sections.